In each plant family I'm beginning to notice remedies that animals take to better than others. I've started this post once before, but I can't find it now. I'll make a note when I haven't tried promising remedies enough. Either way these remedies will open out the others in the group so starting with these is a good idea.
Cicuta in the Umbelliferae group (Conium, Zizia, Petroselinum, Hydrocotyle, Asafoetida, Aethusa). I haven't tried Aethusa enough.
Ignatia in the Loganaceae (Nux vom, Spigelia, Curare, Gelsemium)
Rhododendron will open Ericaceae for Uva Usi and others to work.
Ranunculaeceae has Helleborus which works wonders but needs Aconite, Puls, Staph and esp. Ran b, Ran Sc for months to open up the case for it.
Compositae has the same problem - all the remedies work but they need Absinth, Arnica and Echinacea for months to open up the case for Taraxicum and Carduus Mar to work.